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/* Copyright (c) 2006-2013 by OpenLayers Contributors (see authors.txt for
* full list of contributors). Published under the 2-clause BSD license.
* See license.txt in the OpenLayers distribution or repository for the
* full text of the license. */
/**
* @requires OpenLayers/Geometry/Collection.js
* @requires OpenLayers/Geometry/LinearRing.js
*/
/**
* Class: OpenLayers.Geometry.Polygon
* Polygon is a collection of Geometry.LinearRings.
*
* Inherits from:
* - <OpenLayers.Geometry.Collection>
* - <OpenLayers.Geometry>
*/
OpenLayers.Geometry.Polygon = OpenLayers.Class(
OpenLayers.Geometry.Collection, {
/**
* Property: componentTypes
* {Array(String)} An array of class names representing the types of
* components that the collection can include. A null value means the
* component types are not restricted.
*/
componentTypes: ["OpenLayers.Geometry.LinearRing"],
/**
* Constructor: OpenLayers.Geometry.Polygon
* Constructor for a Polygon geometry.
* The first ring (this.component[0])is the outer bounds of the polygon and
* all subsequent rings (this.component[1-n]) are internal holes.
*
*
* Parameters:
* components - {Array(<OpenLayers.Geometry.LinearRing>)}
*/
/**
* APIMethod: getArea
* Calculated by subtracting the areas of the internal holes from the
* area of the outer hole.
*
* Returns:
* {float} The area of the geometry
*/
getArea: function() {
var area = 0.0;
if ( this.components && (this.components.length > 0)) {
area += Math.abs(this.components[0].getArea());
for (var i=1, len=this.components.length; i<len; i++) {
area -= Math.abs(this.components[i].getArea());
}
}
return area;
},
/**
* APIMethod: getGeodesicArea
* Calculate the approximate area of the polygon were it projected onto
* the earth.
*
* Parameters:
* projection - {<OpenLayers.Projection>} The spatial reference system
* for the geometry coordinates. If not provided, Geographic/WGS84 is
* assumed.
*
* Reference:
* Robert. G. Chamberlain and William H. Duquette, "Some Algorithms for
* Polygons on a Sphere", JPL Publication 07-03, Jet Propulsion
* Laboratory, Pasadena, CA, June 2007 http://trs-new.jpl.nasa.gov/dspace/handle/2014/40409
*
* Returns:
* {float} The approximate geodesic area of the polygon in square meters.
*/
getGeodesicArea: function(projection) {
var area = 0.0;
if(this.components && (this.components.length > 0)) {
area += Math.abs(this.components[0].getGeodesicArea(projection));
for(var i=1, len=this.components.length; i<len; i++) {
area -= Math.abs(this.components[i].getGeodesicArea(projection));
}
}
return area;
},
/**
* Method: containsPoint
* Test if a point is inside a polygon. Points on a polygon edge are
* considered inside.
*
* Parameters:
* point - {<OpenLayers.Geometry.Point>}
*
* Returns:
* {Boolean | Number} The point is inside the polygon. Returns 1 if the
* point is on an edge. Returns boolean otherwise.
*/
containsPoint: function(point) {
var numRings = this.components.length;
var contained = false;
if(numRings > 0) {
// check exterior ring - 1 means on edge, boolean otherwise
contained = this.components[0].containsPoint(point);
if(contained !== 1) {
if(contained && numRings > 1) {
// check interior rings
var hole;
for(var i=1; i<numRings; ++i) {
hole = this.components[i].containsPoint(point);
if(hole) {
if(hole === 1) {
// on edge
contained = 1;
} else {
// in hole
contained = false;
}
break;
}
}
}
}
}
return contained;
},
/**
* APIMethod: intersects
* Determine if the input geometry intersects this one.
*
* Parameters:
* geometry - {<OpenLayers.Geometry>} Any type of geometry.
*
* Returns:
* {Boolean} The input geometry intersects this one.
*/
intersects: function(geometry) {
var intersect = false;
var i, len;
if(geometry.CLASS_NAME == "OpenLayers.Geometry.Point") {
intersect = this.containsPoint(geometry);
} else if(geometry.CLASS_NAME == "OpenLayers.Geometry.LineString" ||
geometry.CLASS_NAME == "OpenLayers.Geometry.LinearRing") {
// check if rings/linestrings intersect
for(i=0, len=this.components.length; i<len; ++i) {
intersect = geometry.intersects(this.components[i]);
if(intersect) {
break;
}
}
if(!intersect) {
// check if this poly contains points of the ring/linestring
for(i=0, len=geometry.components.length; i<len; ++i) {
intersect = this.containsPoint(geometry.components[i]);
if(intersect) {
break;
}
}
}
} else {
for(i=0, len=geometry.components.length; i<len; ++ i) {
intersect = this.intersects(geometry.components[i]);
if(intersect) {
break;
}
}
}
// check case where this poly is wholly contained by another
if(!intersect && geometry.CLASS_NAME == "OpenLayers.Geometry.Polygon") {
// exterior ring points will be contained in the other geometry
var ring = this.components[0];
for(i=0, len=ring.components.length; i<len; ++i) {
intersect = geometry.containsPoint(ring.components[i]);
if(intersect) {
break;
}
}
}
return intersect;
},
/**
* APIMethod: distanceTo
* Calculate the closest distance between two geometries (on the x-y plane).
*
* Parameters:
* geometry - {<OpenLayers.Geometry>} The target geometry.
* options - {Object} Optional properties for configuring the distance
* calculation.
*
* Valid options:
* details - {Boolean} Return details from the distance calculation.
* Default is false.
* edge - {Boolean} Calculate the distance from this geometry to the
* nearest edge of the target geometry. Default is true. If true,
* calling distanceTo from a geometry that is wholly contained within
* the target will result in a non-zero distance. If false, whenever
* geometries intersect, calling distanceTo will return 0. If false,
* details cannot be returned.
*
* Returns:
* {Number | Object} The distance between this geometry and the target.
* If details is true, the return will be an object with distance,
* x0, y0, x1, and y1 properties. The x0 and y0 properties represent
* the coordinates of the closest point on this geometry. The x1 and y1
* properties represent the coordinates of the closest point on the
* target geometry.
*/
distanceTo: function(geometry, options) {
var edge = !(options && options.edge === false);
var result;
// this is the case where we might not be looking for distance to edge
if(!edge && this.intersects(geometry)) {
result = 0;
} else {
result = OpenLayers.Geometry.Collection.prototype.distanceTo.apply(
this, [geometry, options]
);
}
return result;
},
CLASS_NAME: "OpenLayers.Geometry.Polygon"
});
/**
* APIMethod: createRegularPolygon
* Create a regular polygon around a radius. Useful for creating circles
* and the like.
*
* Parameters:
* origin - {<OpenLayers.Geometry.Point>} center of polygon.
* radius - {Float} distance to vertex, in map units.
* sides - {Integer} Number of sides. 20 approximates a circle.
* rotation - {Float} original angle of rotation, in degrees.
*/
OpenLayers.Geometry.Polygon.createRegularPolygon = function(origin, radius, sides, rotation) {
var angle = Math.PI * ((1/sides) - (1/2));
if(rotation) {
angle += (rotation / 180) * Math.PI;
}
var rotatedAngle, x, y;
var points = [];
for(var i=0; i<sides; ++i) {
rotatedAngle = angle + (i * 2 * Math.PI / sides);
x = origin.x + (radius * Math.cos(rotatedAngle));
y = origin.y + (radius * Math.sin(rotatedAngle));
points.push(new OpenLayers.Geometry.Point(x, y));
}
var ring = new OpenLayers.Geometry.LinearRing(points);
return new OpenLayers.Geometry.Polygon([ring]);
};
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